1. Field of the Invention:
The Invention concerns thermoplastic molding materials of a polyphenylene ether, a graft polymer, a functionalized polyethylene, a polyamide and optionally further polymers and additives.
2. Discussion of Background:
Polyphenylene ethers are high-performance industrial thermoplastics with high viscosities and softening points. They are suitable for numerous technical applications in which high temperature stability is important. These polycondensates are described among others in U.S. Pat. No. 3,306,874; 3,306,875; 3,257,357 and 3,257,358. They have, however, the disadvantage that they are brittle. In addition, polyphenylene ethers have poor workability, i.e., due to their high softening points and viscosities, high temperatures and high sheer forces must be applied, which may result in damage to the polymer.
Attempts have therefore been made to improve the workability of polyphenylene ethers and the impact strength of the products by the admixture of other polymers.
Primarily, mixtures of polyphenylene ethers with high impact polystyrene are known.
There are also mixtures of polyphenylene ethers with polyamides. These mixtures have good flowability and good resistance to solvents (DE-AS 16 94 290). Usually, however, brittle products are obtained, as the components are incompatible and they are difficult to disperse into each other. Aromatic polyamides, such as those used for example according to EP-OS 0 131 445 are, furthermore, difficult to work together with polyphenylene ethers. Better compatibility of the two phases may be obtained by the functionalizing of the polphenylene ethers, for example with maleic anhydride, in the presence of radical formers (J 59 066 452). However, the use of radical formers leads to an undesirable and uncontrolled partial gelling of the polyphenylene ether phase.
It has therefore been proposed to increase the compatibility of the two polymers by the addition of an adequate amount of a solvent, for example, an organic phosphate (EP-OS 0 129 825) or a diamide (EP-OS 0 115 218). These technical solutions are not adequate, as the improved compatibility must be purchased by significantly reduced high temperature shape retention. Molding materials to which copolymers of styrene and unsaturated acid derivatives have been added, exhibit the same disadvantage. (See EP-OS 0 046 040).
The object of EP-PS 0 024 120 consists of resin masses consisting of a polyphenylene ether, a polyamide, a third component and optionally of high molecular weight rubber polymers. As the third component, a liquid diene polymer, an epoxy compound or a compound with a double or triple bond and a functional group (such as for example an acid, anhydride, ester, amino or alcohol group) is used. However, the impact strength of the resin material obtained is not sufficient for numerous applications.